#include<reg52.h>
#define uchar unsigned char
#define uint unsigned int
void delay(uint z);
void main()
{
	while(1)
	{
		P1=0x00;
		delay(500);
		P1=0xff;
		delay(500);
	}
}
void delay (uint z)
{
	uint x,y;
	for(x=z;x>0;x--)
		for(y=11;y>0;y--);
}